usb: gadget: Export recommended BESL values

Currently there's no option for the controller driver to report the
recommended Best Effort Service Latency (BESL) when operating with LPM
support. Add new fields in usb_dcd_config_params to export the
recommended baseline and deep BESL values for the function drivers to
set the proper BESL value in the BOS descriptor.

Signed-off-by: Thinh Nguyen <thinhn@synopsys.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

include/linux/usb/gadget.h

@@ -291,6 +291,9 @@ struct usb_dcd_config_params {
 #define USB_DEFAULT_U1_DEV_EXIT_LAT	0x01	/* Less then 1 microsec */
 	__le16 bU2DevExitLat;	/* U2 Device exit Latency */
 #define USB_DEFAULT_U2_DEV_EXIT_LAT	0x1F4	/* Less then 500 microsec */
+	__u8 besl_baseline;	/* Recommended baseline BESL (0-15) */
+	__u8 besl_deep;		/* Recommended deep BESL (0-15) */
+#define USB_DEFAULT_BESL_UNSPECIFIED	0xFF	/* No recommended value */
 };